Wave springs have been used in various ways, for example, as a damper for buffering impact in clutch engagement of a clutch mechanism, and the like. The wave spring is a ring-shaped (annular) spring having plural mountain portions.
Wave springs have mountain portions comprising high mountain portions and low mountain portions, whereby the spring constant thereof is changed at a process of the stroke when a load is applied. Specifically, a wave spring may be disposed between a first member and a second member. In this case, the top portion of the high mountain portion is contacted with the first member, and a valley portion is contacted with the second member. When a load is applied to the first member toward the second member, the spring is elastically deformed such that the height of the high mountain portion is decreased. When only the high mountain portion is contacted with the first member, for example, as shown in FIG. 5, a linear characteristic with the spring constant K1 is shown. When the low mountain portion is also contacted with the first member at a process of elastic deformation of the spring, the high and low mountain portions are contacted with the first member, whereby a linear characteristic with the spring constant K2 which is larger than the spring constant K1 is shown.
Such a wave spring is disclosed in, for example, Patent Publications 1 and 2. In the wave spring disclosed in Patent Publication 1, a combination of a high mountain portion and a low mountain portion is repeated at an equal interval. In a wave spring disclosed in Patent Publication 2, a combination of plural mountain portions (a high mountain portion and plural low mountain portions) and a valley portion is repeated at an equal interval, and the low mountain portions are formed with an equal interval in combination.
Patent Publication 1 is Japanese Unexamined Patent Application Publication No. 2005-282807.
Patent Publication 2 is Japanese Utility Model Publication No. 2586112.